Sound focusing

What you can do here
You need another person for this experiment. Stand in front of the two parabolic antennas on the painted foot marks are and try to talk facing each other. Then turn towards your antennas and talk to each other again.


How it works
When you face the antennas, you can easily hear each other – even when you whisper. The sounds you make travel in space as soundwaves. As the sender-recipient distance increases, the sound intensity quickly diminishes. However, when we talk to the antenna, it reflects the soundwaves and directs them towards the other antenna whose parabolic shape focuses the reflected waves. If you put your ears in the spot where they converge called the focal point, you will hear amplified sounds.


Interesting facts
Elliptical-section surfaces provide another example of objects that focus sound waves. They were used in rooms where it was possible for a person in one ellipse focal point to eavesdrop on people talking in another one.
Reflecting soundwaves and focusing them in one spot is also what the pinna does. The focal point is, in that case, the auditory canal. The conclusion is simple: the bigger your ears, the better you hear.